<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        /*浮动的标签是顶对齐的*/
        /*在一行排列，宽高可生效*/
        /*注意：浮动后的标签不能text-align:center margin: 0 auto*/
      .one {
          width: 100px;
          height: 100px;
          float: left;
          background-color: pink;
          margin-top: 50px;
      }
      .two {
          width: 200px;
          height: 200px;
          float: left;
          background-color: skyblue;
      }
      .three {
          width: 300px;
          height: 300px;
          background-color: orange;
      }
    </style>

</head>
<body>
<div class="one">one</div>
<div class="two">two</div>
<div class="three">three</div>
</body>
</html>